The present invention relates to polyethers which are derived from the polymerization of a perfluoroolefin epoxide, and, more particularly, to an improved process for neutralizing acid end groups of such polyethers by replacing them with fluorine radicals.
U.S. Pat. No. 3,242,218 describes a process for preparing fluorocarbon polyethers of the following structure: EQU X--CF.sub.2 --CF.sub.2 --O--[CF(X)--CF.sub.2 --O--]n--CF.sub.2 --X
where n is a positive integer including zero and represents the number of --CF(X)--CF.sub.2 --O-- units in the molecule and where X is a member of the class consisting of fluorine and the perfluoromethyl radical. The process involves the polymerization of a perfluoroolefin epoxide, such as hexafluoropropylene epoxide and tetrafluoroethylene epoxide, to form a perfluorinated acid having the general formula EQU CF.sub.3 --CF.sub.2 --CF.sub.2 --O--[CF(CF.sub.3)--CF.sub.2 --O]n--CF(CF.sub.3)COOH
where n can range from 0 to 35 inclusive, and then heating the acid with fluorine to replace the carboxylic end group with a fluorine radical. The decarboxylation is generally very slow, and, although raising the reaction temperature can raise the reaction rate, elevating temperatures may result in vapor phase explosions.
U.S. Pat. No. 3,399,179 describes the decarboxylation of organic carboxylic acids with fluorine. It is stated that one or more carboxy groups can be replaced directly by fluorine atoms without regard for the exact nature of the organic portion of the molecule since the fluorination reaction occurs at the site of the carboxy group. However, the use of a substantially inert moderator, i.e., a polar or non-polar material in which the acid compound being decarboxylated is at least partially soluble, is an essential part of the decarboxylation reaction.